Field of the Invention
The invention first relates to a device for the fluid-tight sealing of two partially overlapping packaging components, one being a tubular base member, in particular formed from a blank of composite cardboard/plastics material, and an additional packaging component forming the upper packaging portion or packaging base, having at least one mandrel and one die, the mandrel having at least two expansion elements which are moved from the operating position thereof towards each other into a rest position to reduce the cross-section in order to allow ease of sliding-on of the tubular base member, the expansion elements having sealing jaws which, in the operating position thereof, form a closed circumferential outer contour which corresponds to an inner contour formed by an opening in the die, there remaining between the inner contour and outer contour a narrow annular gap in order to apply a pressing force from the inner side to the overlap region of the packaging components and the expansion elements each being pivotably arranged on a common base element, and a corresponding method for sealing.
Description of Related Art
Containers of a composite cardboard/plastics material for, in particular fluid, foodstuffs have been commercially available for some time in an extremely wide variety of shapes and formats. The composite structure, in addition to the carrier layer of cardboard and an inner and outer plastics material layer in each case, may also have other layers, such as, for example, an oxygen barrier layer of aluminium. With regard to the production thereof, a distinction is made in particular between containers from individual blanks and those containers which are produced from roll material on so-called tube forming machines.
In order to produce containers from individual blanks, an already grooved and printed blank is formed by sealing two opposing edges using a so-called longitudinal seam to form a so-called packaging cover, a tubular base member which is then closed at the dispenser to first form a container which is open at one side, formed and subsequently sterilised, filled, and which finally becomes a complete packaging by the other side being closed.
Most commercially available packagings are produced themselves at the ends thereof by means of folding and sealing of the tubular base member. For specific packaging shapes, an end can also be formed by a prefabricated shaping member as an additional packaging component which in turn can be prefabricated individually from plastics material or fibre material (pulp). It is thereby possible to produce any geometric constructions, in particular with regard to the size and arrangement of shaped opening or pouring elements.
Such a container is known from the German patent application DE 10 2010 014 993 A1. In this instance, the shaping member which forms the upper portion of the container is formed to be so large that the circumference thereof substantially corresponds to that of the tubular base member. However, this is not necessarily the case and containers are also known in which the cross-section of the tubular base member first narrows in order to then be able to be connected at the tapered end thereof to an upper portion (DE 10 2010 050 502 A1 or DE 39 42 319 A1).
Furthermore, a sealing device is also described in the older German patent application 10 2013 107 429.4 from the same applicant, the disclosure content of which is referred to with regard to the basic structure of the mandrel for this application. This mandrel has no leaf spring elements for pivotably securing the expansion elements.
Based on this, an object of the invention is to configure and develop a device corresponding method for sealing in such a manner that the kinematics and synchronisation of the expansion elements are optimised. Furthermore, it is desirable to have a simple, low-wear but also reliable and easily cleaned construction by means of which aseptic filled packagings can also be produced. In spite of high output speeds when operating the packaging machines that are equipped therewith, a uniform pressing force is intended to be provided over the entire circumference of the connection components during production.
This object is achieved with a device according to the invention in that each expansion element is secured to at least one torsion-resistant leaf spring element which enables precise pivoting of the respective expansion element between the rest position and operating position. In this manner, it is possible to determine, for example, in the case of a substantially square cross-section, precise direction vectors which are directed at 45° into the “corners” and which consequently also allow secure sealing at that location. Owing to the precise directional guiding, the wear of the surfaces which slide past each other can also be minimised.
According to the invention, the kinematics of the expansion elements is significantly improved by the leaf spring elements. Furthermore, the wear of the sealing elements and also of the guiding elements (resilient deformation at the material inner side) can be significantly reduced. Since the leaf spring elements are planar, individual components with smooth surfaces, the ease of cleaning of the mandrel is significantly improved. In particular, as a result of the precise guiding of the expansion elements, a uniform pressing force is applied over the entire circumference of the connection components and consequently optimal sealing of the packagings produced in this manner is achieved.
With regard to a method according to the invention, the object is achieved by carrying out the following steps:                supplying an unfolded tubular base member,        pushing the base member onto a mandrel which has expansion elements,        supplying a die which has an opening,        supplying an additional packaging component to the mandrel,        introducing the connection heat,        pressing the base member and additional packaging component against the die by unfolding the expansion elements in order to form a continuous outer contour in the contact region of the sealing jaws,        connecting the base member and additional packaging component,        folding-in the expansion elements,        removing the die, and        removing the unit comprising the base member and additional packaging component.        connecting the base member and additional packaging component,        folding-in the expansion elements,        removing the die, and        removing the unit comprising the base member and additional packaging component.        
According to another aspect of teaching of the invention, the leaf spring elements are arranged in a substantially vertical manner and thus extend parallel with the extension direction of the expansion elements. Additional leaf spring elements may also be arranged horizontally. These additional leaf spring elements are preferably arranged between two opposing expansion elements. This arrangement reliably prevents deflection, rotation or tilting and consequently any torsion of the expansion elements.
Preferably, the vertically arranged leaf spring elements are secured in the lower portion of the expansion elements and the leaf spring elements themselves are secured, for example, to a base which is arranged on a mandrel wheel. In the device according to the invention, a plurality of base elements which have the foldable mandrels are preferably secured to a mandrel wheel. They are first arranged so as to be distributed over the circumference of the mandrel wheel and it is further possible, with mandrel wheels of an appropriate width, for a plurality of parallel-extending rows of mandrels arranged circumferentially also to be provided beside each other. In this manner, it is possible with a relatively small structural size to achieve large throughputs in the production or filling of packagings.
Since, in the preferred, previously mentioned construction, the expansion elements are connected to each other only in the lower region thereof, it is particularly advantageous when, according to another aspect of teaching of the invention, additional leaf spring elements are secured in the upper portion of the expansion elements and are secured with the lower free ends thereof to a common centring element. This centring element primarily serves to synchronise the movement processes when the expansion elements are unfolded and folded in. It is preferably retained only by means of the additional leaf spring elements and is not retained or guided in any other manner so that, when the expansion elements are unfolded or folded in, the centring element can move freely in a vertical direction.
An alternative embodiment makes provision for the leaf spring elements to extend over the entire length of the expansion elements as far as the sealing jaws.
An advantageous development of the invention makes provision for the expansion elements to be designed as magnet armatures, at least in the region of the sealing jaws thereof. If, in addition, the die then has one or more magnet coil(s) around the opening thereof, a particularly elegant and small drive solution can be produced. Preferably, the axial height of the magnet armatures corresponds to the height of the magnet coil(s). The magnetic forces on the expansion elements can be varied by means of a skilled selection of the inherent masses of the magnet armatures and the geometric construction and position thereof.
Another embodiment of the invention makes provision for the die to be formed in an integral manner over the circumference of the opening thereof. In this manner, the opening in the die can receive the mandrel and no additional drives or support elements are required in order to be able to absorb the reaction forces during the actual sealing operation.
According to another aspect of teaching of the invention, the die may also have elements for introducing the connection heat. In the case of connection by means of ultrasound welding, these elements for connection may comprise at least one ultrasound sonotrode within the die, the sealing jaws acting as an anvil in this instance. Alternatively, it is also possible for hot air openings to be provided within the die and/or within the sealing jaws as elements for introducing the connection heat if the introduction of connection heat is intended to be carried out by means of application of hot air.
In another embodiment of the invention, the supplying of the additional packaging component is carried out at the same time as the supplying of the die by the opening of the die being formed to secure the additional packaging component. In this instance, the removal of the die and the pulling off of the unit comprising the base member and additional packaging component can then also be carried out advantageously at the same time, whereby the number of necessary processing steps can be considerably reduced.
According to the invention, the unfolding and folding-in of the expansion elements are carried out in precisely determined directions. In this manner, an optimal application of an adequate pressing force can be achieved during the connection operation, particularly in the “corner regions”.
According to another aspect of teaching of the invention, the connection itself can then be carried out by means of ultrasound or by means of hot air together with the pressing operation described above.
In the method according to the invention, it is either possible for the unfolding of the expansion elements to be carried out magnetically and the folding-in to be carried out by means of resilient force or, alternatively, the unfolding of the expansion elements can also be carried out with resilient force and the folding-in in magnetically. According to another embodiment of the invention, there is a third possibility that the reversal of the folding movement is carried out by means of magnetic pole reversal. The determination of the respective drive situation is dependent on various factors, such as, for example, the force distribution, energy use, structural size, in particular with smaller packaging formats, etc.